So hence the reason I was interested in the hAP range. MikroTik are not that well known in the UK but I was interested when I saw them on Broadbandbuyer. It sounds like the mini is a little under powered but I punted out the £20 and bought one anyway. I've on good terms with the cafe I was talking about, it's 200m from my office so I'm going to plug it in and give it a go for a week. But the hAP sounds a more suitable device with 64MB of RAM.
hAP ac^2 is very much in the same price range as hAP and offers 5MHz radio too.
If the mini works for you I think it is quite ok. As a bonus it draws very little electric power (3.5 W).
Out of interest, what kind of things take up RAM in a router? My knowledge of networking overall is pretty good but I've never dug in deep to what actually goes on inside. The operating system will obviously need RAM for it's own variable storage. I infer that there is a "Per connection" overhead, i.e. the router OS allocates a certain amount of RAM for each connection? As a sometimes (games) programmer, I'm thinking about how a router OS works.
You have, in order of relevance for your intended use:
* Connection tracking for NAT/firewall
* IP/IPv6 route cache (the system assigns max sizes depending on RAM)
* DNS cache ( " )
* standing DHCP leases
* firewall rules, which are not a problem unless you use things like blacklisting or similar that involve address lists.
* wireless registration-table (connections). Those are purged quickly
* If you are using traffic shaping, queues take RAM
* If you are using PPP-based VPNs, the user list goes on RAM, and of course dynamic interfaces...
* If you are using IPsec, identities and standing associations
* Of course, once you start going OSPF, BGP... there are more things that take RAM
For a bar I would say none of these are going to bite you if you use a short DHCP lease duration. Default is 10m, quite reasonable. For connection tracking, the "tcp-established-timeout: 1d" is a bit too generous, I often see stale connections from phones that went to sleep. If you start to have upstream flapping problems the established TCP connections remain there for about 1 day. I have just now 25 stale connections (of ~100) in my home router with only a couple of phones and laptops. Those come from sleeping/waking up several times yesterday
Some traffic queueing might come handy to ensure bandwidth sharing is fair, specially if the connection becomes saturated, but I'd only look there after checking how it works in practice.